Pneumatic tire leak detector

ABSTRACT

An apparatus for detecting the location of a leak in a pneumatic tire. A leaking tire is filled with a suspension which is capable of flowing through a leak of the tire and staining the perimeter of the leak at the outside surface of the tire. The suspension is a powdered fluorescent pigment of small particle size suspended in a propellant and the air inside of the tire. A portable container is provided for storing the powdered pigment and propellant. The container has an outlet valve for controlling the release of the pigment and propellant from the container. One end of a flexible tube is connected to the outlet valve of the container and a fitting at the other end of the tube is connected to an inlet valve of the tire. The fitting has a means for sealing the attachment of the tube to the tire inlet valve and a means for opening the tire inlet valve. When the outlet valve of the container is opened, the pigment and propellant flow into the tire and combine with the air in the tire to form the suspension. The escape of the suspension through the leak deposits some of the powdered pigment on the perimeter of the leak which is easily seen for detecting the location of the leak.

This is a division of application Ser. No. 06/750,591 filed July 1,1985, now U.S. Pat. No. 4,612,798.

BACKGROUND OF THE INVENTION

The detection of large leaks in pneumatic tires is rarely a problemsince the noise created by the escaping air leads one directly to thearea of the leak. The detection of smaller leaks requires far moreeffort since the noise may be inaudible and the source of the leaknearly invisible with the naked eye. Tire leaks can occur frompunctures, defective sealing at the tire/rim interface and defectivetire inlet valves.

The usual procedure for detecting the location of leaks involvesde-mounting a leaking tire from a vehicle, partially submerging the tirein a water tank and searching for bubbles caused by escaping air. Thisprocedure is time consuming and especially frustrating since leaks frompunctures are most common and tire punctures are commonly repaired withexternally inserted elastomeric repair plugs--a process which does notrequire de-mounting punctured tires from their vehicles.

In view of the foregoing, a means for detecting small leaks in pneumatictires without de-mounting and immersing them in water would save muchlabor and time. Such means would also make possible repairs in the fieldfor even greater savings.

SUMMARY OF THE INVENTION

The present invention is related to tire repair and more particularly toan apparatus for detecting the locations of small leaks withoutde-mounting the tires from their vehicles and immersing them in water.

A powdered pigment and propellant are stored under pressure in acontainer commonly referred to as an "aerosol can". The container has amanually operable outlet valve and one end portion of a flexible tubularline connected to the outlet side of the valve. A fitting is connectedto the other end portion of the flexible line and the fitting is adaptedfor connecting the line to the inlet valve of a tire. On manuallyopening the container outlet valve with the flexible line connected to atire inlet valve, powdered pigment is injected under pressure by thepropellant into the tire, filling it with an aerosol suspensioncomprising the powdered pigment suspended in the air and a propellant.The aerosol suspension escaping through the leak carries the powderedpigment to the outer surface of the tire and stains the perimeter of theleak on the outer surface of the tire, thereby providing a visualmarking of the leak.

It is a primary object of the invention to provide an improved means ofidentifying the location of a tire leak.

It is another object in addition to the foregoing object to identify thelocation of a leak without de-mounting the tire from a vehicle.

It is another object in addition to the foregoing objects to provide avisual means for detecting the location of a leak.

It is another object in addition to the foregoing objects to facilitaterepairs of tires on the road.

It is another object in addition to the foregoing objects to reduce thetime and labor for repairing a leaking tire.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a leak detecting apparatusconnected to the inlet valve of a tire.

FIG. 2 is an enlarged diametral cross-sectional view taken through theinlet valve of a tire with the leak detecting apparatus connected to theinlet valve.

FIG. 3 is a perspective view of a fitting for connecting a flexible tubeto the inlet valve of a tire.

FIG. 4 is a perspective view of an alternate embodiment of the fittingof FIG. 3 for connecting the flexible hose to the inlet valve of thetire.

FIG. 5 is an alternate embodiment of the leak detecting apparatus ofFIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings wherein like numerals refer to like andcorresponding parts throughout the several views, the leak detectorapparatus 9 is shown in operation in FIGS. 1 and 2. In accordance withthe present invention there is provided a powdered pigment 10 forforming an aerosol or semi-aerosol suspension 11 of a powdered pigment10, a propellant 20 and air 38 inside a leaking tire 12. There is alsoprovided a conventional aerosol can 15, for storing the powdered pigment10 and a propellant 20, comprising a sealed portable container 17, amanually operable outlet valve 18 mounted in the top portion of thecontainer 17 and a pick-up tube 19 communicating from said valve 18 tothe bottom of said container 17.

A flexible tube 23 is provided for conveying the pigment/propellantmixture 26 of the aerosol can 15 from the outlet valve 18 to an inletvalve 25 of the tire 12. One end portion of the tube 23 is fixedlyattached to the outlet portion of the container valve 18 by clamping orsome other suitable means. The other end portion of the flexible tube 23is provided with a suitable conventional type fitting 24 to connect thetube 23 to the tire inlet valve 25.

The conventional fitting 24 which is illustrated in FIG. 3 is commonlyused for connecting the distal end portion of an inflation hose to atire inlet valve. This type of fitting 24 has internal threads 29 whichengage external threads 30 on the end portion of the tire valve 25.

FIG. 4 illustrates another suitable type of conventional fitting 28which is easy to use and is also commonly used in bicycle pumps forconnecting an inflation hose to a tire inlet valve. When used, thefitting 24 is placed over the tire valve 25 and the fitting lever 27rotated to form a seal and open the tire valve 25. The fittings 24 and28 illustrated in FIGS. 2 and 3 are but two types of available fittings.Means (not shown) are provided in the fittings 24 and 28 for sealing theconnection of the flexible tube 23 to the tire inlet valve 25 and foropening the tire inlet valve 25 to admit the pigment/propellant mixture26 into the tire 12. Obviously, any type of fitting which could connectand seal the flexible tube 23 to the tire valve 25 and open the valve 25could be used.

The container 17 is charged with a two phase Freon propellant 20 or someother suitable propellant such as a hydrocarbon propellant. In theportable container 17, as oriented in the drawings, vapor phase 21occupies the upper portion of the container 17 and liquid phase 22occupies the lower portion. The particles of pigment 10 are dispersed inthe liquid phase 22 forming the pigment/propellant mixture 26. Uponmanually opening the outlet valve 18, the propellant 20 forces thedispersion of pigment 10 in the liquid propellant 22 up the pick-up tube19 and through the valve 18 making the powdered pigment 10 available forinjection into the tire 12.

Some of the pressurized pigment/propellant mixture 26 is released intothe flexible tube 23 connected by the fitting 24 to the tire inlet valve25. Expansion and evaporation of the liquid propellant phase 22 combinedwith the velocity of injection of the mixture 26 through the tire valve25 disperses the pigment particles 10 to suspend the powdered pigment 10in the air 38 of the tire 12 and the propellant 20 and form an aerosolor semi-aerosol suspension 11 throughout the interior of the tire 12.

Referring back to FIG. 1, the escape of the aerosol suspension 11through the tire puncture 13 deposits some of the powdered pigment 10onto the outer tire surface 14 around the perimeter of the puncture 13causing a visible stain 31 for locating the puncture 13.

Several parameters determine how well the powdered pigment 10 willindicate the location of a leak 13. First the pigment 10 must be capableof adhering well enough to the outer surface 14 of the tire 12 toprovide a visible marking 31 or staining on the perimeter of the leak13. Secondly, the pigment 10 should be highly visible in order tominimize the amount of pigment 10 that must be transported through theleak 13 to be visible.

Since the rate of transport of the powdered pigment 10 through a leak 13depends on the quantity of suspension 11 flowing through the leak 13, amore visible pigment 10 will develop a stain 31 more quickly and therebybe a more sensitive indicator of small leaks 13. Fluorescent typepigments 10 are especially attractive in this regard.

Thirdly, the powdered pigment 10 must be fine enough in size to form anaerosol or semi-aerosol suspension 11 so that escaping suspension 11 cantransport particles of pigment 10 through the leak 13. Since a longerlived suspension 11 will improve the sensitivity to small leaks 13, atrue aerosol suspension 11, i.e., less than one micron particle size, ishighly desirable because the particles of pigment 10 would then staysuspended indefinitely. However, for most cases a semi-aerosolsuspension 11 i.e., greater than one micron particle size, will havesufficient duration to indicate the location of the leak 13. Preferably,the particle size of the powder 10 should be under 10 microns.

One suitable available powdered pigment 10 is Dayglo (registeredtrademark) Series AX manufactured by the Dayglo Corporation. It isfluorescent and has been found to be effective for staining the outertire surface 14. The pigment 10 is in the form of amorphous individualparticles (not crystalline or agglomerate) having a rather small averageparticle size of 3.5-4.0 microns, which is advantageous for dispersionof the powder 10 both in the tire 12 and in the aerosol can 15. Theparticle size of the powder 10 can be further reduced, if desired, byprocessing in a roll or ball mill. Obviously, other powdered pigments 10fulfilling the aforementioned requirements can also be used.

An alternative embodiment 32 of the invention is disclosed in FIG. 5,wherein an external source of compressed gas propellant, such ascompressed air 38, is used in place of the pre-charged propellant 20 formixing with the powdered pigment 10 and conveying the mixture to theinterior of a tire 12. This embodiment 32 comprises, a pressuresustaining container 33, a closure 34 threadably connected to the upperportion of the container 33, an inlet fitting 35 mounted on the closure34, a flexible line 36 fixedly connected to the inlet fitting 35 foradmitting compressed air 38 into the container 33, a manually operatedoutlet valve 37 mounted on the closure 34 for releasing a mixture of air38 and powdered pigment 10, a flexible tube 41 fixedly attached to theoutlet valve 37 for transporting the mixture of air 38 and powderedpigment 10 to the interior of the tire 12 and a fitting 24 connected toone end portion of the outlet valve 37 for connecting the flexibleoutlet tube 41 to the inlet valve 25 of the tire 12.

The container 33 is initially charged by removing the closure 34 andfilling the container 33 with only powdered pigment 10. The closure 34is then sealed by threadably engaging the closure 34. Operation of theoutlet valve 37 causes an inrush of compressed air into the container33, entraining and dispersing the powdered pigment 10, and transportingthe dispersion through the outlet valve 37, through the flexible outlettube 41 and into the interior of the tire 12. In a similar manner as thefirst embodiment 9, the velocity and expansion of the air 38 forms anaerosol or semi-aerosol suspension 11 of powdered pigment 10 inside thetire 12.

From the foregoing it will be appreciated that the present inventionprovides an effective and convenient means for detecting the location ofleaks in a tire which does not require de-mounting of a tire from avehicle and is suitable for repairing tires on the road.

Although but two embodiments of my invention have been disclosed, itwill be further appreciated that other embodiments can be provided bychanges in material, shape, arrangement and detail of what has beendisclosed without departing from the spirit and scope thereof as definedby the appended claims.

I claim:
 1. A leak detector apparatus for detecting the location of aleak in a pneumatic tire comprising in combination:(a) a pressuresustaining container adapted for storing a powdered pigment and apropellant; (b) a propellant stored inside of said container fortransporting the powdered pigment to the interior of a tire; (c) apowdered pigment stored inside of said container for visually indicatingthe location of a leak in said tire, said powdered pigment being of amaterial and a fine enough particle size to be transported by saidpropellant from the container to the interior of the tire, thence tocombine with said propellant and air inside the tire to form asuspension of powdered pigment throughout the interior of the tire, andthence to flow through and stain the perimeter of a puncture in the tireto visually detect the location of a leak in the tire; (d) a means forregulating the discharge of said powdered pigment and propellant fromsaid container; and (e) a means for conveying said powdered pigment andpropellant from said container to the interior of said tire.
 2. The leakdetector apparatus recited in claim 1 wherein said powdered pigment is afluorescent pigment.
 3. The leak detector apparatus recited in claim 1wherein said powdered pigment is of a fine enough particle size to forman aerosol suspension of powdered pigment throughout the interior of thetire.
 4. The leak detector apparatus recited in claim 1 wherein saidpowdered pigment is of a fine enough particle size to form asemi-aerosol suspension of powdered pigment throughout the interior ofthe tire.
 5. The leak detector apparatus recited in claim 1 wherein saidpropellant is a Freon propellant.
 6. The leak detector apparatus recitedin claim 1 wherein said propellant is a hydrocarbon propellant.
 7. Thepneumatic leak detector cited in claim 1 wherein the means for conveyingthe powdered pigment and propellant from the container to the interiorof the tire comprises:(a) a flexible tube; (b) a fitting attached to oneend portion of said tube for connecting said tube to an outlet of saidcontainer; and (c) a fitting attached to the other end portion of saidtube for connecting said tube to an inlet valve of the tire, saidfitting having a means for sealing the attachment of the tube to theinlet valve and a means for opening the tire inlet valve.
 8. A leakdetector apparatus for detecting the location of a leak in a pneumatictire comprising in combination:(a) a pressure sustaining container forstoring a powdered pigment; (b) a powdered pigment stored inside of saidcontainer for visually indicating the location of a leak in said tire,said powdered pigment being of a material and a fine enough particlesize to be transported by a propellant from the container to theinterior of the tire, thence to combine with said propellant and airinside the tire to form an aerosol suspension of powdered pigmentthroughout the interior of the tire, and thence to flow through andstain the perimeter of a puncture in the tire to visually detect thelocation of a leak in the tire; (c) a closure threadably connected tosaid container for adding said powdered pigment; (d) an inlet fittingmounted on said closure for admitting a propellant into said container;(e) a propellant for transporting the powdered pigment to the interiorof a tire; (f) a manually operated outlet valve mounted on said closurefor controlling the discharge of powdered pigment and propellant fromsaid container; (g) a flexible tube for conveying said powdered pigmentto said tire; (h) a fitting attached to one end portion of said tube forconnecting said tube to the outlet valve mounted on said closure; and(i) a fitting attached to the other end portion of said tube forconnecting said tube to an inlet valve of the tire, said fitting havinga means for sealing the attachment of the tube to the inlet valve and ameans for opening the tire inlet valve.
 9. The leak detector apparatusrecited in claim 8 wherein said propellant is a compressed gas.